Apparatus for automatic regulation of rectifiers and rotary converters.



F. B. OROOKER.

APPARATUS FOR AUTOMATIC REGULATION OF REGTIFIERS AND ROTARY CONVERTERS.

APPLICATION FILED APRL4,1908.

1,012,524 Patented 1)ec.19,1911.

4 SHEETSSHEET l.

| L Hh. In

Witnesses hgyenlor, 5 y g 'ra nris B. CF00 (e1:

Af/orny F. B. OROOKER. APPARATUS FOR AUTOMATIC REGULATION OF REOTIFIERSAND ROTARY CONVERTERS. APPLICATION FILED APR. 4, 1908. 1,012,524 vPatented Dec. 19,1911.

4 SHEETS-SHEET 2 Witnesses; Inventor;

hfgj gf Francis B Cracker,

C by A fi F. B. CROOKER. APPARATUS FOR AUTOMATIC REGULATION OFRBGTIFIERS AND ROTARY CONVERTERS.

APPLICATION FILED APR. 4, 1908.

1,012,524, Patented Dec. 19,1911.

4 SHEETSSHEET 3.

Fig. 5.

Witnesses: Invenlor,

@ZMWZ Frahcjs B. Cracker;

v byavw fugryff v F. B. OROOKER, APPARATUS FOR AUTOMATIC REGULATION OFREGTIFIERS AND ROTARY CONVERTERS.

' APPLICATION FILED APR. 4, 1908.

1,012,524, Patented Dec. 19,1911.

4 SHEETSSHEET 4.

Fig. 7. Zero Load.

1000 AT I C O 1" g -100v 550V 650V Fig. 8. V t Half Load.

Fig. 9. Full Load. I m 2000 E3440 A-T 1 g O 2800 AT 650V.

\Nitnesses Inventor, @WMEC }k g ,,4- Francis BCroaker: wan/z (26% by Kmp,

FRANCIS B. CROGKER, OF NEW YORK, N. Y.

APPARATUS FOR AUTOMATIC REGULATION OF REOTIFIERS AND ROTARY CONVERTERS.

Specification of Letters Patent.

Patented Dec. 19, 1911.

Original application filed July 25, 1904, Serial No. 218,053. Dividedand this application filed April 4,

1908. Serial No. 425,110.

To all whom it may concern;

Be it known that I, FRANCIS B. CRocKER, a citizen of the United Statesof America, and a resident of the city, county, and State of New York,have invented certain new and useful Improvements inA paratus forAutomatic Regulation of Recti ers' and R0- tary Converters, of which thefollowing is a specification.

This invention relates to an apparatus for the automatic regulation ofelectric currents in conjunction with thGlI COIIVQI'SlOII fIOIDalternating current into direct current or from direct current intoalternating current by any suitable rectifier. or rotary converter.

The object of the invention is to provide a simple and effectiveapparatus without moving parts to secure automatic regulation byinductive action between the alternating current circuits as modified bythe influence of the direct current. In this way it is possjble to causethe voltage to remain con-= stant or to rise with increase of load, andso overcome the drop of potential ,that usually takes place inthegenerator, transmitting lines, transformer, and other parts of thecircuits when under load. A typical form of this apparatus comprises amagnetizable core with series and shunt coils connected to thealternating current leads through which current passes to the rectifier,and a series coil connected in one of the direct-current leads of therectifier.

In the accompanying four sheets of drawings which form a part of thisapplication,Figure 1 illustrates an alternator, alternating conductorssupplied therefrom, a rectifier, direct-current circuits suppliedthrough the rectifier from the alternatingcurrent circuit, and a corewith regulating coils and connections, as above indicated. Fig. 2illustrates a modified arrangement,

in which the core has a double magnetic cir-- cuit, and thedirect-current coil is divided into two portions oppositely wound on thetwo parts of the magnetic circuit, to neutralize inductive effects, arotary converter be ing used as a rectifier. Fig. 3 illustrates amodification of the preceding arrangement in which capacity is insertedin the shunt circuit. Fig. 4 illustrates a modification of thearrangement of Fig. 2 in which direct-current shunt coils are employedin addition to the direct-current series coils.

Fig. 5 illustrates a tri-phase alternator with a regulating apparatussimilar to that of Flg. l inserted in each of the threealternating-current leads from the alternator, and a mercury-vaporrectifier. Fig. 6 illustrates a direct-current generator, direct-currentconductors fed thereby, a rotary converter, alternating-current circuitssupplied with energy through the converter from the direct-currentcircuit and a regulating apparatus similar to that illustrated in Fig.2. Figs. 7, 8 and 9 represent by vector diagrams the values and phaserelations at respectively zero, half and full loads existin in aspecific regulating apparatus constructe and operated accordm to myinvention.

Referring first to Fig. 1, a single-phase generator Gr feeds current toalternating current conductors A and B. These conductors supply energythrough a rectifier C to direct-current leads H I which deliver theenergy to direct-current consuming tievices such as storage batterycells P, motors F or lampsQ. The rectifier or rectifying commutatorconsists of slip rings 1' r and a commutator s driven by asynchronousmotor D which revolves in synchronism with the alternations of thecurrentsupplied from the generator. In series with one .of thealternating current conductors A leading to the rectifier is a coil Jwound on a laminated iron core E. A shunt coil N is also wound in thesame direction on the core, and in the arrangement illustrated in thisfigure is connected at one end to a branch from the alternating-currentconductor A between the series coil J and the rectifier. The function ofthis shunt coil is to induce a certain electromotive force in the coil JI acting in the alternating-current circuit in opposition to thatproduced by the generator G. Hence the actual alternating electromotiveforce supplied to the rectifier is less than that of the generator. Athird coil M is also wound on the core, and is connected in series withone of the direct-current leads H. A choke coil T may also be placed inseries in the direct-current circuit to prevent the flow of anyalternating current in this circuit which might otherwise be induced inthe coil M. v

The operation of the apparatus in regu lating current is as follows:When the load in the direct-current circuit is increased,

motive force in for example by theinsertion of additional lamps Q,motors F, or storage batteries 1 to be charged, the additional currentllow in the coil M tends to saturate magnetically the core E so that themutual induction between the alternating-current coils N and J isreduced. The effect of this reduction is to diminish the opposingelectromotive force induced in the coil J by the coil N. The resultantvoltage in the alternating-current circuit will therefore be increased,and the voltage in the direct-current circuit which is supplied by therectified alternating-current will likewise be increased. When themagnetizing effect of the direct-current coil M tends to saturate thecore E, the self-induction of the shunt coil N is reduced so that thecurrent flowing through it will rise in value. In order to prevent thisrise from becoming excessive an inductance L, or a resistance R, or bothmaybe inserted in series with the coil N. if either or both of thesehave a considerable value compared with the self-induction of the coilN, then the variation of that self-induction will not cause too large anincrease of current in the coil. It is convenient to have thisinductance or resistance adjustable, as shown, so as to set or controlthe regulating effects. In order that the initial opposing electromotiveforce may be exactly opposite in phase with respect to the electromotiveforce of the generator, the current in the shunt coil N should lag 90behind the generator electromotive force. The opposing electroturn lags90 behind the shunt current, thereby producing a total phase difl'erenceof 180, or exact opposition.- The reactance due to the inductance L inthe shunt circuit is usually made large compared with the resistance Bso that the current shall have a lag of approximately 90. Anotheradvantage thussecured is the fact that inductance consumes no energywhereas resistance does. Owing to these phase relations the opposingelectromotive force of the coil J results in a transformation ofelectrical energy from it to the shunt coil N At no load thiselectromotive force has full value, but the current being zero theenergy is also zero. With any appreciable loadone-half, for example-thecurrent is also one-half of the full valueand the opposing electromotiveforce should then be approximately one-half of its initial amount inorder that the resultant boosting eflect (t. a. rise in voltage) may benearly proportional to the load. Under these conditions an amount ofenergy equal to the product of one-half of the full current by aboutone-half of the maximum opposin electromotive force (less the losses) istrans erred from the series coil J to the shunt coil N. In consequence alarger current and lower electromotive force than the generator producesmay thus be supplied to the rectifier. L As full load is ap; preached,the main alternating current 111 the series coilJ rises, but itsopposing electromotive force falls owing to the magnetic saturation ofthe iron core by the direct-current coil M. Theoretically thiselectromotive force should become zero at full load. Practically itstill has a fraction of its origi nal value since the magneticsaturation is not complete.

In the arrangement illustrated in Fig. 2 a core is employed having adouble magnetic circuit, the two'parts or paths of which are indicatedby the dotted lines 3 and p. The a]ternating-current coils N and J arewound on the part of the core common to both circuits, and thedirect-current coil is divided into two portions M and M which are.oppositely wound on the other two parts of the magnetic circuit. Thesecoils are therefore balanced with res ect to the alternating fluxinduced by the a ternating-current coils so that no alternating currentis induced in the direct-current coils, and a choke coil in thedirect-current circuit is unnecessary. This balance is less perfect whenthe load increases, because the direct-current magnetization is in onedirection and allows the al-' ternating currents to vary the flux lessin that direction than in the other, especially as saturation isapproached. On the other hand, inductive action, so that objectionableeffects are largely avoided.

In the arrangement illustrated in Fig. 3, capacity K is inserted in theshunt circuit in lieuof the adjustable inductance L. The effect of thiscapacity is to advance the phase relation of the current in the shuntcircuit. Assuming that this advance has its maximum value of 90, theelectromotive force set up in the shunt coil will lag 90 behind thecurrent, hence it will be in phase with the impressed electromotiveforce. It follows therefore that the current in the series winding beingin phase with the impressed electromotive force should be opposite indirection to that in the shunt coil. In other words, the two currentsdivide at their common junction as shown and flow in opposite directionsaround the central portion of the iron core in order that theelectromotive force of the shunt coil may oppose the electromotive forceof the series coil. Ijig. 3 also shows that the shunt coil may drawenergy from the alternating-eurrent conductors directly, instead ofafter the alternating current has passed through the series coil as inthe connections illustrated in the preceding fi ure. In this figure theshunt coil is supp ied by a constant or falling electromotive force, andin Figs. 1 and 2 by a rising electromotive force. The adjustableregulating resistance R, inductance L and capacity K may obviously bethis saturation also tends to diminish used individually or incombinations, and being variable may have various absolute as ell asrelative values. In any case such element orelements of my organizationmay be designated by or included in the general term impedance. p I

The arrangement illustrated in Fig. 4,

employs connections substantially as in Fig.

variationsin load may be accentuated. In

this case it is also a fact that there is an initial direct-currentmagnetomotive force at no load, while in the preceding, arrangement itis proportional to the load.

In the arrangement of Fig. 5, the invention is applied in connectionwith a mercury-vapor rectifier, such as the Cooper- Hewitt rectifier.The regulating devices constituting my invention are inserted in each ofthe three alternating-current leads from a suitable source ofthree-phase current G. The currents through the series coils J J J areled to the positive electrodes E, E E 'in the upper part of themercuryvapor rectifier. The current throughthe shunt coils N N N returnto the neutral point of the three-phase generator. The direct-currentleads H I are connected respectively to the neutral pointof thegenerator and the negative side of the rectifier. The rectifier has afourth positive electrode E through which, and the negative pole of therectifier, current is applied from a suitable source S for starting therectifier.

In the arrangement illustrated in Fig. 6, the invention is applied tothe regulation of electric current in conjunction with its conversionfrom direct into alternating current. A direct-current generator S feedscurrent to direct-current leads H I. These conductors supply energythrough a rotary converter to alternating-current leads A B whichdeliver the energy to consuming devices either directly or throughtransformers. The regulating apparatus is as described in connectionwith Fig. 2, and consists of a series coil J connected -in one of thealternating-current leads, a shunt coil N which is connected across thealtermating-current leads, and a two-part directcurrent series coil M Minserted in one of the direct-current leads through which direct currentreaches the rotary converter. As before, the shunt coil N induces aninitial opposing electromotive force' in the series coil J of thealternating-current circuit,

producing a resultant electromotive force less than that given out bythe converter. The direct-current in the coils M M, increasing directlywith the load, tends to saturate magnetically the core E and suppressthe opposing electromotive force, thus automatically raising theresultant electromotive force of the'alternating-current circuit A B, inaccordance with my invention.

In order to show the phase relations existing in my automatic regulatingdevice and to illustrate how it may be deslgned to fulfil practicalconditions, the following example is given: The arrangement of apparatusand connections illustrated in Fig. 2

is adopted, and the central portion of the iron core E is assumed to be1l 8=88 square inches, each end portion'being half as large or 5 8=44tsquare inches because there are two magnetic circuits. The maximum fluxthrough the central part may be taken as 88 87,000=7,656,000 lines,being 87,000 lines per'square inch or 13,500 lines per squarecentimeter. Each magnetic circuit p or y is 40 inches in length andrequires about 25 ampere-turns per inch or 40x25: 1,000 ampere-turns inthe shunt coil N to produce a flux density of 13,500. At a frequency of60 this flux will set up about 20 volts effective electromotive force ineach turn of the series coil J, so that 5 turns will produce 100 voltsin opposition to the electromotive force of the alternating-currentgenerator G. This opposing electromotive force is represented by theline 0 0 in Fig. 7 and the generator electromotive force by the line 09. Assuming the latter to be 650 volts the resultant alternatingelectromotive-force supplied to the rotary converter (O in Fig. 2) is550 volts at no load, being represented by 0 r in Fig. 7. At half loadthe sei'ies alternating current coil J will carry 280 amperes (maximum)so that its magnetomotive force is280 5=1,400 ampere-turns, and isinphase with the generator electromotive force as indicated by the line 0s in Fig. 8. This combined with Y the shunt ampere-turns 0 t which areas sumed to have increased to 1,500, produces a resultant 0 m of 2,050ampere-turns, being the total alternating magnetomotive force. Assuming13 turns in each of the directcurrent coils M M and a current of 138amperes, the magnetomotive force of each coil is 138x 13 orapproximately 1,800 ampere-turns. This being constant and in onedirection, the alternating magnetomotive force combines with it to givea maximum of l,800+2,050=3,8 50 ampere-turns, and a minimum of 1,'8002,050:250 ampereturns. The variation in flux thus produced will setup in the series alternating-current coil J an electromotive force ofabout 82 volts lagging 90 with respect to the phase of the alternatingmagnetomotive force as represented by the line -0 0 in Fig. 8. Thiselectromotive force acting with that of the generator 0 9 gives aresultant 0 r of 590 volts being 40 volts higher than at zero load.

The magnetic flux produced by the 7,040

maximum ampere-turns is not very much greater than that produced by the1000 ampere-turns at zero load or the 3850 ampere-turns at -half load,because the lI'OIl core is nearly saturated in all three cases. On theother hand, the 160 ampere-turns which is the minimum value .at fullload produces a considerable flux which is in the same direction as themaximum because the magnetomotlve force 1s positive in both cases.

load than at half load or at zero load. The operation of the apparatusdepends upon this very saturation of the magnetic CII cnits. Of coursethis saturation is not complete, but is effective nevertheless, inreducing the electromotive-for'ce generated in the coil J. Anydistortion or shifting of the magnetic flux waves due to the saturation.or direct current magnetization may tend toset up unbalancedelectromotive forces in the parts of the direct-current winding, but theflow of alternating current therein can be checked by the presence ofinductance as represented at t in Fig. 1. The resulting flux variationgenerates an alternating electromotive force of as volts 0 0 in theseries coil J which is combined with 0 g the generator electromotiveforce to form the resultant o. r amounting to 625 v olts, being 35 voltsgreater than at half load, the rise being approximately proportional tothe load. Increase in the shunt current and ampere-turns is due to thedecrease in the inductance of that circuit resulting from the partialsaturation of the iron core by thedirect-current coils M M.. Thisefi'ect may also be produced or increased by connecting the shunt coil Nbeyond the series coil J, as shown in Fig. 2 so that it is fed by anelectromotive force that rises with the load. The presence of resistancein the shunt circuit will tend to reduce the lag of the current. In Fig.2, for example, an increase in the resistance R and a'diminution of theinductance L will have this 'efi'ect; that is, the angle between theshunt-ampere-turns 0 t and the generator electromotive force 0 g Hencethe actual flux variation and electromotive force induced are less atfull becomes less than 90. Other thin s being equal, this will decreasethe efiect o the opposing electromotive force 0 0. Hence by varying theinductance L, or the resistance R, or both, and by altering the relativenumber of turns in the several coils, the regulating action of theapparatus may be set or adjusted to suit different conditions. In theparticular exam le cited, the generator supplies 650 volts e ective and560 amperes maximum, or 397 amperes eflective which gives 258 kilowattsat full load, and the volume occupied by the regulating device is onlyabout 3- 1 1? or, 4-} cubic feet. In the example given, it is notattempted to state the voltages, currents, etc., with exactness, becausethey would depend upon the permeability"of'the iron core and otherpractical conditions. Furthermore it was pointed out that there is atransformer action between the shunt and the series alternatingcurrentcoils, so that the current supplied to the converter or rectifier ismore and the voltage less than in the generator.

I have shown and described some of the forms of apparatus andarrangements by 7 means otwhich my invention may be practiced but itwill be understood that it may be employed in connection with any devicefor converting alternating into direct-current or vice versa. It willalso be understood that the form of the core may be varied to suitdifierent conditions and that it may be of any magnetic material adaptedto thepurpose. Several coils wound upon or a plied to the core may besubdivided or difierently arranged in order to modify or adjust theirefi'ects. It will also be understood that my invention does not residein the connections of the coilsillustrated, and that these may bealtered or reversed in order to change their individual as well asresultant actions.

I do not claim the method herein set forth, as that is claimed in myapplication Serial No. 218,053, filed July 25, 1904, of which this is adivisional application.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. The combination of a plurality of alternating-turrent conductors, aplurality of direct-current conductors, a source of supply for oneof'the sets of conductors, a device connected between these sets ofconductors for converting current of the character of one set to that ofthe character of the other set, and a regulator comprising a core inwhich alternating flux andinductiveaction are set up by the alternatingcurrent with a series winding connected in the main circuit of thealternating-current conductors, a shunt winding connected between the'main alternating-current conductors and a vwinding connected to thedirect-current conducto'rs, substantially as described.

2. The combination of a plurality of alternating-c1irrent conductors, aplurality of direct-current conductors, a source of supply forone of thesets of conductors, a device connected between these sets of conductorsfor converting current of the character of one set to that of thecharacter of the other set, a shunt connection for the mainalternating-current conductors, and a regulator comprising avInagnetizable core with a series winding connected in the main circuitof the direct-current conductors, a series winding connected in the maincircuit of the altcrnating-current conductors, and a shunt windingincluded in the shunt connection, substantially as described. 1 x

3. The combination of a plurality'of alternating-ciu'rent conductors, aplurality of directcurrent conductors, a source of-supply for thealternating-current conductors, a rectifying apparatus connecting thesets of conductors, and an automatic regulator comprising amagnetizable' core-in which alternating flux and inductive action areset up by the alternating-current with a series winding connected in themain circuit of the alternating-current conductors, a *shunt windingconnected between 'the mainalternating-current conductors and a serieswinding connected in the main circuit of the direct-current conductors,substantially as described.

4. The combination of a plurality of alternating-current conductors, aplurality of direct-current conductors, a source of supply for thealternating-current conductors, a rectifying device connecting the setsof conductors, a shunt connection to the main alternating-currentconductors, and an au} tomatic regulator comprising a magnetizable corewith a series winding connected in the main circuit of thealternating-current conductors, a series winding connected in the maincircuit of the direct-current conductors, a shunt winding and anadjustable impedance included in the shunt connection, substantially asdescribed.

5. The combination with a plurality of alternating-current conductors, aplurality of direct-current conductors, a source of supply for one ofthe sets of conductors, and

ternating-current conductors, a plurality of direct-current conductors,and a converting or rectifying device connecting the sets of conductors,of a regulator comprisin a magnetlzable core provlded with windlngsconnected in series and m shunt with the main alternating-currentconductors and also provided with series and'shunt Windings connected tothe direct-current conductors, substantially as described.

7. The combination of a plurality of alternating-cm'rent conductors, aplurality of direct-current conductors, a converting or rectifyingdevice connecting the sets of conductors, and a regulator comprising aniron core provided with windings connected in series and in shunt withthe m ain alternatingcurrent conductors, and also provided with windingsconnected in series and in shunt with the main direct-currentconductors, with adjustable impedance in the alternating-current shuntwindings, substantially as described.

Signed by me at New York, N. Y., this 31st day of March, 1908.

I FRANCIS B. OROCKER.

Witnesses:

MonroN ARENDT, C. J. HonsLAe.

